best in what way? if you're talking about risky but profitable then holding cryptocurrencies that have strong support. if you want something with minimal risk but far less return you're better off going with mutual funds.
There is actually nothing called "best" investment. Every investment carries its won risk and if you cant handle it you should steer clear of it. Trading bitcoin/fiat and altcoin are profitable according to me. Mining used to profitable at one time and not so at this point.
People in this forum also earn by using their skills and knowledge to work for others - freelancing. You can also try joining signature campaigns which are very popular, but make sure not to spam the forum but rather make proper constructive posts.
For the time being, there is more unity in the altcoins such as Ethreum or the Monero, that is the people people are buying them.